Exhaust system of a marine vessel

ABSTRACT

An exhaust system for a marine propulsion device is configured to dispose two exhaust conduits in generally concentric overlapping relation with each other in order to minimize the potential cross sectional area of a leak path in the event that a seal fails. One of the exhaust conduits extends through a transom or other surface of a marine vessel and another exhaust conduit conducts exhaust gas from an engine to the exhaust conduit extending through the surface of the marine vessel.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is generally related to exhaust systems of marinevessels and, more particularly, to an exhaust system which directs anexhaust flow to a point external to a marine vessel which is beneath thesurface of a body of water in which the marine vessel is operated.

2. Description of the Related Art

Those skilled in the art of marine vessels and engine systems are awareof many different types of exhaust systems that direct exhaust gas awayfrom an engine. Some marine systems direct the flow of exhaust gas to alocation which is under the surface of a body of water. This is done forseveral reasons, including the silencing effect that can be obtained byexhausting the gases below the water level. The exhaust conduits of amarine propulsion system typically use more than one individual exhaustpipe, or conduit, to direct the exhaust gas from the engine to the pointat which the gas is emitted from the exhaust system. The variouscomponents of the conduit system are connected together, either byflanges or intermediate elastomeric connectors, such as bellowsstructures.

U.S. Pat. No. 3,802,491, which issued to Plank et al. on Apr. 9, 1974,describes a marine exhaust system. It comprises inner and outerconcentrically arranged flexible conductors held in concentric relationby spacers and fittings at the opposite ends. The fitting at one end isadapted to connect the inner and outer conductors, respectively, to themanifold of an engine and to a coolant pump. The fitting at the otherend is adapted to connect the inner and outer conductors, respectively,to a muffler and to an overboard line.

U.S. Pat. No. 4,861,296, which issued to Wlezien on Aug. 29, 1989,describes a marine propulsion device exhaust system. It comprises asterndrive unit including a gimbal housing adapted to be fixed to a boattransom. It also comprises an exhaust gas passage in a propulsion unitwhich includes an outlet normally located underwater and an inletnormally located above the water. A flexible exhaust gas bellows has arearward end connected to the inlet of the gas passage in the propulsionunit and a forward end. An exhaust gas and coolant discharge conduitextends through the gimbal housing and comprises a forwardly locatedinlet passage adapted to receive combined exhaust gas and coolantdischarge from an engine.

U.S. Pat. No. 4,911,666, which issued to Gage et al. on Mar. 27, 1990,describes a boat propulsion device with an internal exhaust. A marinedrive mounts through a hole in the bottom surface of a boat utilizing adriveshaft housing assembly. An engine mounted to the driveshaftassembly and a lower propeller drive unit mounted to the driveshafthousing assembly are also provided. The driveshaft housing assemblymounts the drive within the hole in the boat and includes a driveshafthousing. A steering assembly is constructed to rotate about a generallyvertical axis within the driveshaft housing assembly to providesteering. A trimming assembly is connected to the steering assembly topivotably swing the lower propeller drive unit to provide trimming andtilting. It also comprises a driveshaft and an exhaust passagetherethrough.

U.S. Pat. No. 5,421,756, which issued to Hayasaka on Jun. 6, 1995,describes an exhaust system for the marine propulsion machine. Itprovides an exhaust gas discharge system for a watercraft. The systemhas a first discharge path, including a first outlet, primarily for useduring high speed vessel operation and a second discharge path,including a second outlet, for use during both low and high speed vesseloperation.

U.S. Pat. No. 6,022,254, which issued to Neisen on Feb. 8, 2000,discloses an exhaust system for an inboard/outboard marine propulsionsystem. The exhaust system includes intermediate exhaust pipes which arephysically separate components than the water separator. A sealedlatching mechanism connects an outlet portion of the intermediateexhaust pipes to an inlet portion of the water separator. The sealedlatching mechanism is secure yet flexible and allows the orientation ofthe intermediate exhaust pipe to be adjusted relative to the waterseparator. This allows the exhaust system to be installed and servicedwithout dismounting or loosening the engine. The intermediate exhaustpipes also have a flared inlet part to facilitate alignment of theintermediate exhaust pipe at the exhaust elbow.

U.S. Pat. No. 6,508,681, which issued to Neisen on Jan. 21, 2003,describes a low friction exhaust bellows and techniques for constructingand assembling the bellows. A propulsion system has a low frictionexhaust bellows relative to an engine located in the interior of amarine vessel. The engine has an exhaust discharge member incommunication with a propulsion unit and an exhaust passage having anexterior coupling member flexibly connected to pass exhaust from theexhaust discharge member to the propulsion unit. The interior surface ofthe passage is configured to provide a relatively smooth surface to theexhaust passage therein.

U.S. Pat. No. 7,018,255, which issued to Phillips et al. on Mar. 28,2006, discloses an exhaust system for a marine propulsion device havingtwo stationary tubes to define an annular exhaust passage. The system isprovided with inner and outer bellows, or tubes, which are rigidlyattached to both the transom bracket and the driveshaft housing of asterndrive system. Neither the inner nor outer tubes rotate with thedriveshaft. Both the inner and outer tubes, or bellows, allow thedriveshaft to rotate relative to the transom bracket about either asteering axis or trim axis. An exhaust passage is defined between theouter surface of the inner tube and the inner surface of the outer tube.

The patents described above are hereby expressly incorporated byreference in the description of the present invention.

When an exhaust system of a marine vessel conducts the flow of exhaustgases to a point below the surface of a body of water in which themarine vessel is operated, any leak or rupture of the exhaust systembelow the surface level of the water can cause water to flow into themarine vessel. Bilge pumps are typically provided and are intended toremove water from the bilge of the marine vessel but, in many instances,the bilge pump has a limited flow capability and may not be able toremove water from the bilge at the rate that it is leaking into thebilge. This is particularly true if a catastrophic failure occurs in anexhaust conduit at a point below the surface of the body of water. Itwould therefore be significantly beneficial if this potentially seriousproblem could be alleviated.

SUMMARY OF THE INVENTION

An exhaust system of a marine vessel made in accordance with a preferredembodiment of the present invention comprises a first exhaust conduitand a second exhaust conduit. An end portion of the second exhaustconduit is disposed within an end portion of the first exhaust conduit.A seal is disposed between the end portion of the second exhaust conduitand the end portion of the first exhaust conduit. The seal can bedisposed between an outer surface of the end portion of the secondexhaust conduit and an inner surface of the end portion of the firstexhaust conduit.

In a preferred embodiment of the present invention, the seal can be anelastomeric seal which, in turn, can be a lip seal. The end portion ofthe second exhaust conduit and the end portion of the first exhaustconduit can be generally concentric.

A preferred embodiment of the present invention further comprises anengine connected in fluid communication with the first and secondexhaust conduits and a surface of a marine vessel. The first and secondexhaust conduits are configured to conduct a stream of exhaust gas fromthe engine through the surface, which can be a transom of a marinevessel.

In a preferred embodiment of the present invention, it further comprisesa marine propulsion drive connected in torque transmitting relation witha crankshaft of the engine. The marine propulsion drive can be asterndrive unit. The stream of exhaust gas can be conducted through thetransom of the marine vessel and through the sterndrive unit.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more fully and completely understood froma reading of the description of the preferred embodiment in conjunctionwith the drawings, in which:

FIG. 1 shows an exhaust pipe connection known to those skilled in theart;

FIG. 2 is an exploded view of a preferred embodiment of the presentinvention;

FIG. 3 is an assembled view of the structure shown in FIG. 2;

FIGS. 4 and 5 show the geometric advantages of the present invention;

FIG. 6 shows an embodiment of the present invention;

FIG. 7 shows the present invention used in conjunction with a sterndrivesystem; and

FIG. 8 shows the present invention used in conjunction with an inboarddrive system.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Throughout the description of the preferred embodiment of the presentinvention, like components will be identified by like referencenumerals.

FIG. 1 shows the manner in which two exhaust conduits are typicallyconnected in marine propulsion devices known to those skilled in theart. An exhaust pipe 10 which is connected to an engine (not shown inFIG. 1) is attached to an exhaust pipe 12 which conducts the flow ofexhaust gas E to and through a transom or hull of a marine vessel.Functionally, an engine and its exhaust manifold would be located to theleft of the illustration in FIG. 1 and the transom or lower hull of themarine vessel is located to the right of the schematic representation inFIG. 1. The ends of the exhaust pipes 10 and 12, which face each other,are identified by reference numerals 16 and 18, respectively. Theseends, 16 and 18, can be butted together or spaced apart as shown inFIG. 1. An elastomeric connection member 20 is typically attached toboth exhaust pipes, 10 and 12, by clamps which are schematicallyrepresented in FIG. 1 and identified by reference numerals 22 and 24.The elastomeric connection member 20 allows some relative movementbetween the two exhaust pipes, 10 and 12, and provides a seal thatprevents the escape of exhaust gas from the region within theelastomeric connection member 20. Naturally, if a leak forms through theelastomeric connection member 20 or if the clamps, 22 and 24, becomedisconnected, exhaust gas can escape from that region and, moreimportantly, water can flow from a point external to the marine vesselto the end face 18 and into the bilge of the marine vessel. This type ofleak is possible when the stream of exhaust gas E is directed throughthe transom at a point which is below the surface of the water in whicha marine vessel is operated. For example, the marine propulsion unitdescribed in U.S. Pat. No. 4,911,666 extends through the bottom surfaceof a marine vessel. Any leak in the exhaust system below the level ofthe water can result in a flow of water from the body of water into themarine vessel bilge. Similarly, the marine propulsion system describedin U.S. Pat. No. 6,022,254 can potentially develop a leak within theexhaust conduits inside the marine propulsion device and below the levelof the body of water.

FIG. 2 is a schematic representation of an exhaust system joint made inaccordance with a preferred embodiment of the present invention. Itcomprises a first exhaust conduit 31 and a second exhaust conduit 32. Anend portion 42 of the second exhaust conduit 32 is disposable within anend portion 41 of the first exhaust conduit 31. A seal 40 is disposedbetween the end portion 42 of the second exhaust conduit 32 and the endportion 41 of the first exhaust conduit 31 as will be described below inconjunction with FIG. 3. In the exploded view of FIG. 2, the first andsecond exhaust conduits, 31 and 32, are shown spaced apart and the seal40 is shown between them. In a preferred embodiment of the presentinvention, the seal 40 is made of an elastomeric material and, in aparticularly preferred embodiment, is a lip seal.

FIG. 3 is similar to FIG. 2, but with the components assembled together.In FIG. 3, the seal 40 is shown disposed between the end portion 42 ofthe second exhaust conduit 32 and the end portion 41 of the firstexhaust conduit 31. In this preferred embodiment shown in FIG. 3, theseal 40 is disposed between an outer surface 52 of the end portion 42 ofthe second exhaust conduit 32 and an inner surface 51 of the end portion41 of the first exhaust conduit 31. The seal 40 can be an elastomericseal, as described above, and a lip seal. In a preferred embodiment ofthe present invention, the end portion 42 of the second exhaust conduit32 and the end portion 41 of the first exhaust conduit 31 are generallyconcentric.

FIGS. 4 and 5 are provided to illustrate the primary advantage providedby the present invention. FIG. 4 is a simplified representation of across section of an exhaust pipe. The cross section shown in FIG. 4 isthe cross section through which water would flow from the body of waterinto the bilge of a marine vessel if the two exhaust conduits areseparated. As an example, the illustration in FIG. 4 shows a sectionview of the exhaust pipe 12 described above in conjunction with FIG. 1.The flow of water, from a body of water and into the boat, would flowthrough the internal area of the exhaust pipe 12. If, on the other hand,the exhaust system incorporated the principles of the present invention,as illustrated in FIG. 3, and the elastomeric seal 40 fails, water islimited to flowing in the region identified by reference numeral 140 inFIG. 5, between the outer surface of the second exhaust conduit 42 andthe inner surface 51 of the first exhaust conduit 41. If clearancesbetween the first and second exhaust conduits are limited appropriately,this cross sectional area 140 can be significantly less than the areawithin the exhaust pipe 12 shown in FIG. 4.

FIG. 6 shows an embodiment of the present invention in which an externalclamp is used to maintain the axial relative positions of the first 31and second 32 exhaust conduits. The seal 40 is shown with the radiallyinward extension deformed slightly as a result of the contact with theouter surface 52 of the second exhaust conduit 32. A circumferentialridge 200 of the second exhaust conduit facilitates the clamping of thefirst and second exhaust conduits together as shown. A plurality ofbolts 202, nuts 204, washers 206 and springs 208 facilitate theretention of the two exhaust conduits in relation to each other. Inaddition, two clamp rings, 210 and 212, assist in providing the axialretention forces.

FIG. 7 is a schematic representation of the general location of thepresent invention in relation to a marine vessel and its engine anddrive unit. The engine 300 has a manifold 302 from which exhaust gasesare emitted. It should be understood that the engine 300, manifold 302and drive unit 304 are represented in a highly schematic manner in FIG.7. The purpose of FIG. 7 is to illustrate the relative positions of thevarious components and not to show the precise way in which they areconnected to each other. As those skilled in the art of marinepropulsion devices are well aware, many different configurations areprovided in exhaust systems and many types of interconnections betweenvarious components are well known. The general direction of the exhaustflow is represented by arrows E in FIG. 7. The first exhaust conduit 31extends through the transom 310 of a marine vessel. This directs theflow of exhaust gas E through the marine drive unit 304 which can be asterndrive unit.

With continued reference to FIG. 7, it can be seen that the connectionbetween the first and second exhaust conduits, 31 and 32, is relativelylow within the bilge of the boat. In some applications, the exhaustconnection in the region of the seal 40 can be below the water line ofthe surface of the body of water in which the marine propulsion systemis being operated. In those cases, hydrostatic pressure will cause waterto rise within the first exhaust conduit toward the engine. A failure ofthe seal between the first and second exhaust conduits can thereforelead to a flow of water into the bilge of the boat. One advantage of thepresent invention is that such a failure, of the seal 40, will lead to asignificantly reduced flow of water into the bilge if the seal fails,whereas a failure of the connector 20 in FIG. 1, as typically used inthe prior art, can lead to a much more catastrophic failure. Thisdifference is described above in conjunction with FIGS. 4 and 5.

FIG. 8 is a schematic representation of a section view of a marinevessel with an inboard drive system. The crankshaft 400 of the engine300 provides torque to a transmission device 402 which, in turn,provides torque to a propeller shaft 404. The propeller shaft has apropeller attached to its distal end (not shown in FIG. 8). The basicconfiguration of the exhaust conduit is generally similar to thatdescribed above. If the connection region between the first and secondexhaust conduits, 31 and 32, is below the water level of the body ofwater in which the marine propulsion system is operated, a failure ofthe seal between the two exhaust conduits can lead to the flow of waterinto the bilge of the boat as a result of the hydrostatic pressureexperienced by that region of the exhaust conduit structure. Again, thepresent invention limits that flow of water.

With reference to FIGS. 2-8, it can be seen that an exhaust system for amarine vessel made in accordance with a preferred embodiment of thepresent invention, comprises a first exhaust conduit 31, a secondexhaust conduit 32, and end portion 42 of the second exhaust conduit 32which is disposed within an end portion 41 of the first exhaust conduit31, and a seal 40 disposed between the end portion 42 of the secondexhaust conduit 32 and the end portion 41 of the first exhaust conduit31. The seal 40 is disposed between an outer surface 52 of the endportion 42 of the second exhaust conduit 32 and an inner surface 51 ofthe end portion 41 of the first exhaust conduit 31. The seal 40 can bean elastomeric seal and, in certain embodiments of the presentinvention, can be a lip seal. The end portion 42 of the second exhaustconduit and the end portion 41 of the first exhaust conduit aregenerally concentric in a preferred embodiment of the present invention.An engine 300 is connected in fluid communication with the first andsecond exhaust conduits, 31 and 32, and a surface of a marine vessel,such as a transom surface, is provided such that the first and secondexhaust conduits direct a stream of exhaust gas from the engine 300through the surface. The surface can be a transom 310 of a marinevessel. The marine propulsion drive, such as a sterndrive unit 304 or apropeller shaft 404 is connected in torque transmitting relation with acrankshaft 400 of the engine.

It should be understood that many different sizes of first and secondexhaust conduits can be used in various embodiments of the presentinvention. The advantage of the physical arrangement provided by thepresent invention is that the outer diameter of the second exhaustconduit 32 and the inner diameter of the end 41 of the first exhaustconduit 31 can be selected to minimize the circumferential gap betweenthose surfaces. This gap defines the radial thickness of the seal andfurther defines the area through which water can pass if the seal fails.This area can be selected to limit the flow of water, in the event of acatastrophic failure, to that which can be accommodated by a bilge pump.On the other hand, if the flow of water in this type of failure mode islimited only to the internal area of the first exhaust conduit, the flowof water into the bilge can easily exceed the capability of the bilgepump. These relative areas are discussed above in conjunction with FIGS.4 and 5. The primary advantage of the present invention is, therefore,its ability to inherently limit the flow of water into the bilge of aboat from the body of water in which the boat is operated when acatastrophic failure occurs in the seal between the first and secondexhaust conduits.

Although the present invention has been described with particularspecificity and illustrated to show a preferred embodiment, it should beunderstood that alternative embodiments are also within its scope.

1. A marine vessel exhaust system, comprising: a first exhaust conduit;a second exhaust conduit, an end portion of said second exhaust conduitbeing disposed within an end portion of said first exhaust conduit; anda seal disposed between said end portion of said second exhaust conduitand said end portion of said first exhaust conduit.
 2. The exhaustsystem of claim 1, wherein: said seal is disposed between an outersurface of said end portion of said second exhaust conduit and an innersurface of end portion of said first exhaust conduit.
 3. The exhaustsystem of claim 2, wherein: said seal has a radial inward extensiondeformed along a taper as it extends from said inner surface of said endportion of said first exhaust conduit to said outer surface of said endportion of said second exhaust conduit.
 4. The exhaust system of claim2, wherein: said seal extends from said inner surface of said endportion of said first exhaust conduit to said outer surface of said endportion of said second exhaust conduit such that increasing exhaustpressure in said exhaust conduits increases sealing pressure applied bysaid seal between said exhaust conduits.
 5. The exhaust system of claim2, wherein: said end portion of said second exhaust conduit and said endportion of said first exhaust conduit are generally concentric inaxially overlapped relation, and comprising a ridge formed on one ofsaid exhaust conduits facilitating clamping of said exhaust conduitstogether and limiting and defining axial travel therebetween.
 6. Theexhaust system of claim 2, further comprising: an engine connected influid communication with said first and second exhaust conduits; and asurface of a marine vessel, said first and second exhaust conduits beingconfigured to conduct a stream of exhaust from said engine through saidsurface; wherein said seal has a radially inward extension deformedalong a taper as it extends from said inner surface of said end portionof said first exhaust conduit to said outer surface of said end portionof said second exhaust conduit; said seal extends along said taper suchthat increasing exhaust pressure in said exhaust conduits applied tosaid taper increases sealing pressure applied by said seal between saidexhaust conduits.
 7. The exhaust system of claim 6, wherein: saidsurface is a transom of said marine vessel.
 8. The exhaust system ofclaim 6, further comprising: a marine propulsion drive connected intorque transmitting relation with a crankshaft of said engine.
 9. Theexhaust system of claim 2, wherein: said end portion of said secondexhaust conduit and said end portion of said first exhaust conduit aregenerally concentric in axially overlapped relation, and comprisingaxial retention clamp rings providing axial retention force retainingsaid exhaust conduits in axially clamped relation.
 10. The exhaustsystem of claim 9 comprising one or more axial biasing members providingaxially biased clamping force between said exhaust conduits.
 11. Amarine vessel exhaust system, comprising: a first exhaust conduit; asecond exhaust conduit, an end portion of said second exhaust conduitbeing disposed within an end portion of said first exhaust conduit; aseal disposed between said end portion of said second exhaust conduitand said end portion of said first exhaust conduit; an engine connectedin fluid communication with said first and second exhaust conduits; anda surface of a marine vessel, said first and second exhaust conduitsbeing configured to conduct a stream of exhaust gas from said enginethrough said surface.
 12. The exhaust system of claim 11, wherein: saidseal is disposed between an outer surface of said end portion of saidsecond exhaust conduit and an inner surface of end portion of said firstexhaust conduit; said seal has a radially inward extension deformedalong a taper as it extends from said inner surface of said end portionof said first exhaust conduit to said outer surface of said end portionof said second exhaust conduit; said seal extends along said taper suchthat said taper is exposed to increasing exhaust pressure in saidexhaust conduits such that said increasing exhaust pressure appliedagainst said taper increases sealing pressure applied by said sealbetween said exhaust conduits.
 13. The exhaust system of claim 12,further comprising: a marine propulsion drive connected in torquetransmitting relation with a crankshaft of said engine.
 14. The exhaustsystem of claim 13, wherein: said end portion of said second exhaustconduit and said end portion of said first exhaust conduit are generallyconcentric in axially overlapped relation; and comprising a ridge formedon one of said exhaust conduits facilitating clamping of said exhaustconduits together and limiting and defining axial travel therebetween;and comprising axial retention clamp rings providing axial retentionforce retaining said exhaust conduits in axially clamped relation; andcomprising one or more axial biasing members providing axially biasedclamping force between said exhaust conduits.
 15. The exhaust system ofclaim 14, wherein: said seal is an elastomeric lip seal.
 16. The exhaustsystem of claim 14, wherein: said surface is a transom of said marinevessel.
 17. The exhaust system of claim 16, wherein: said marinepropulsion drive is a stemdrive unit and said stream of exhaust gas isconducted through said stemdrive unit.
 18. A marine vessel exhaustsystem, comprising: a first exhaust conduit; a second exhaust conduit,an end portion of said second exhaust conduit being disposed within anend portion of said first exhaust conduit; a seal disposed between anouter surface of said end portion of said second exhaust conduit and aninner surface of end portion of said first exhaust conduit, said endportion of said second exhaust conduit and said end portion of saidfirst exhaust conduit being generally concentric in axially overlappedrelation; an engine connected in fluid communication with said first andsecond exhaust conduits; and a surface of a marine vessel, said firstand second exhaust conduits being configured to conduct a stream ofexhaust gas from said engine through said surface, wherein: said sealhas a radially inward extension deformed along a taper as it extendsfrom said inner surface of said end portion of said first exhaustconduit to said outer surface of said end portion of said second exhaustconduit; said seal extends along said taper such that said taper isexposed to increasing exhaust pressure in said exhaust conduits whichincreasing exhaust pressure applied to said taper increases sealingpressure applied by said seal between said exhaust conduits; andcomprising a ridge formed on one or said exhaust conduits facilitatingclamping of said exhaust conduits together and limiting and definingaxial travel therebetween; and comprising axial retention clamp ringsprovides axial retention force retaining said exhaust conduits inaxially clamped relation; and comprising one or more axial biasingmembers providing axially biased clamping force between said exhaustconduits.
 19. The exhaust system of claim 18, further comprising: amarine propulsion drive connected in torque transmitting relation with acrankshaft of said engine.
 20. The exhaust system of claim 19, wherein:said surface is a transom of said marine vessel, said marine propulsiondrive is a stemdrive unit and said stream of exhaust gas is conductedthrough said stemdrive unit.